The present invention relates to picture distribution systems and methods, picture distributing apparatuses and methods therefor, picture receiving apparatuses and methods therefor, and recording media and programs used therewith, and in particular, to a picture distribution system and method, a picture distribution apparatus and a method therefor, and a picture receiving apparatus and a method therefore in which pictures can be distributed without overloading a network, and a recording medium and a program which are used therewith.
A new picture-space service is in the process of being launched. In the new picture-space service, from pictures having various viewpoints, such as omnidirectional pictures, a user can selectively view a picture from a user-preferred viewpoint. Multi-viewpoint pictures such as omnidirectional pictures have large amounts of data since they include pictures constituting the space, other than a picture (or a displayed picture) being actually viewed by the user.
When the streaming distribution of the multi-viewpoint pictures is performed by a transmission link such as the Internet, in the existing streaming distribution systems, such as REALSERVER® of RealVideo and QUICKTIME® of Apple, all pictures constituting the picture space are distributed from a server to a client. This is because an application such as transmission of omnidirectional pictures is not assumed.
Japanese Unexamined Patent Application Publication No. 11-205772 describes the network distribution of omnidirectional pictures. In the invention in this Publication, the transmitting side transmits all pictures, while the receiving side separates a picture to be displayed. In this type of distribution method, there is a large load on network bands since all the pictures are distributed despite that most of the pictures are not displayed. Also, when the displayed pictures have compressed form, decoding size increases, thus increasing the processing load on the client. This causes a problem in that real-time processing is difficult.
Accordingly, an approach is required in which only the necessary pictures are distributed without distributing all the pictures. In Japanese Unexamined Patent Application Publication No. 2000-132674, a system is proposed in which a viewpoint picture of omnidirectional pictures is transmitted and received. In the proposed system, a client uses coordinates to designate a viewpoint picture, and a server transmits only a picture at the designated coordinates. The proposed system is based on the assumption that it is mainly used for still pictures. Thus, in response to a user's urgent viewpoint-moving request, a picture from the requested viewpoint cannot be provided due to a delay in response on the network, so that a smooth viewpoint movement is not realized.